Fluid pressure device



March 24, 1942. H. c. BOWEN 2,277,292

FLUID PRESSURE DEVICE Filed Aug. 23, 1940 INVENTOR.

ATTORNE Patented M11524, 1942 I N1TEo' s'rirr s:

SLPATENQT ,omcs 1 L aziiizez FLUID rnEssUR r DEVICE Herbert C. Bowen, Detroit, Mich, assignbr to Hydraulic Brake Company, Detroit, Mich., a

corporation of California Application august 2;, 1940, Serial ,No. 353,581

/ 9Claims. torso-54m t having a filling opening l4 normally'closed as bya plug 16 having openings 18 therethrough for cating therewith, and a piston movable in the chamber for creating pressure. The piston has a small, chamber concentrically disposed therein,

' and a correspondingly small piston received by the small chamber for creating pressure on the fluid therein carrying means {or releasing pressure on the fluid'in the large chamber.

c An object of the inventionv is to provide. a

low pressure'produci-ng means and a high pres-;

sure producing" means, and means for release of pressure on the fluid in the low pressure .pro-

ducing means afterattaining a predetermined pressure and simultaneously transferring the .pressure from the low pressure producing means to-the high pressure producing means.

Another object of the-invention is to provide a two-phasesfluid pressure producing means operative to maintain a predetermined pressure at'all times so as to avoid loss of motion, partic-' ularly during the initial actuation of the pressure' producing means.

Another object of the invention is to provide a fluid pressure producing device including a low pressure producing means and a high pressure producing means operative concomitantly; and to effect a transition from low to high pressure without materially increasingthe applied activating force. Y V

'A' feature of the invention is,a fluid pressure producing device including a reservoir, a" cylinder communicating therewith, and telescopic pistons in the cylinderf'or creating pressure on the fluid, one manually actuated and the other mov-" able within certain limits by pressure on the fluid, and means carried by the'latter for control of the communi'cation'between the reservoir and the cylinder. F

Othnobjects and advantages of the invention will appear from the following description taken in connection with the drawing forming apart of this specification, and in which fluid pressu re Fig. '1 is a 'schem tic view of a system embodying the invention; and

Fig.v 2 is a vertical sectional view of a fluid pressure producing device incorporated in the i system. r

sure producing device including a. reservoir I2 Referringtc the drawing formore specificde tails of the invention, It! represents a fluid presventing the reservoir to-the atmosphere. I

'A cylinder at the base of the reservoir includes 4 I a chamber 22 and-a chamber 24 arranged forward -of, concentric to and in direct communication with the chamber 22 andprovides'at its junc-, tion with the cylinder 22'an annular shoulder 26.

I ,7 The chamber 24 is closed as by a head 28 provided with a concentric opening 30. Arranged in the wall of the cylinder is a port 32 providing a comreservoir, and a'port 34 providing a communication between the chamber 24 and-the reservoir.

' A piston 36 reciprocable in the chamber 22 is held against displacement by a washer 38 seated on a'shofulderfin the open endof the chamber 22 and secured in place by a retaining ring 40 seated in a groove in the wall of the chamber. The piston 36 includes a head 42 having thereon a sealing cup 44, and a'body portion 46 supports va sealing ring 48' for inhibiting seepage of fluid from the cylinder pastjthe, piston. The piston 36 has an extension 50, andthis extension and the body portion ofthe piston are bored to provide a chamber 52 opening directly into that portion 'of'the chamber 22 forward of the piston, and arranged in the wall of the extension is'a port 54 providing a ccmmunication between the 30' chambers 22 and 52. g

' A pistonjfi reciprocablejin the opening 30 in the-head 28 of the chamber 24 has a circumferential flange providing a head 58, restricted in its movementbetween the annular shoulder 26 and the head 28o-f the chamber 24. A sealing cup seated on the head 28 embraces the piston 56 to inhibit-seepage of fluid past the piston 56, and a spring 64 interposed between the cup and the back of the piston 56 serves to retain the cup against displacement and also to normally retain the head 58 4- againstthe annular shoulder .26; The head 58 "has a ;plurality of spaced passages 66 therethrough 'providing=communications be tween the cylinders 22 and 24,'and a sealing cup 68 on the head 56 controls the passages and also serves to seal the head 58 on the, annular shoulder 26, and a spring H! interposed between the washer-onthe head 58 and thesealing cup 44 serves to retainthe washer and cup against displacement andalso to return the piston 36 to its retracted position.

' The piston. 56 also has a head 12 movable in the'charfiber-Sl The headZ'IZ has avplurality of spaced passages 14 threthrough providing communications between the chamber and the 'munication between the chamber 22 and the,

chamber 52. The head 12 and the body of the piston 68 are axially bored toprovide a passage 14 therethrough, and the outer end of this passage is enlarged and threaded for attachment of a fluid pressuredelivery pipe or conduit.

A sealingcup 18 seated on the head 12 controls the passages 16, and a spring 80 interposed between the bottom of the chamber 52 and the cup serves to retain the cup against displacement. The cup 18 is provided with a centrally disposed conical opening .2 providing a controlled communication between the chamber 52 and the passage through the piston 58. The opening 82 is of such character that the fluid in the passage 18 and the fluid pressure delivery lines connected to this passage is maintained under a predetermined pressure.

A fluid pressure delivery line or conduit 84 connected to the passage 16 has branches connected respectively to fluid pressure actuated mo tors 86, preferably arranged in pairs, one pair for actuating brakes associated with the front wheels of a vehicle, and another pair, for actuating brakes associated with the rear wheels of the vehicle.

The brakes are of conventional type, each including a flxed support or backing plate 88, a

I connected as by a flexible boot I02 to the open end of the cha'mber22 for the exclusion of dust and other foreign substances. A rod I04 connects the coupling to a foot pedal lever I06, rockably mounted on a stub shaft I", and connected by a retractile spring I II to a fixed support It is to be realized that for a successful operation of the device the combined strength of springs II and ll is less than the strength of spring 84. In a normal operation, upon depressing the foot pedal lever I", force is transmitted therefrom through the rod "4 and thrust pin 90 to the piston ll, resulting in movement of the piston on its compression stroke.- During the initial movement of the piston 34 on its compression stroke,the sealing cup 44 on the head of the piston closes the port 32, and thereafter,

as the piston proceeds on its compression stroke,

fluid is displaced from the chamber 22, through the passages 14 in the head" of the piston 50, beneath the cup 18 thereon, thence through the passage 18 and fluid pressure delivery line or conduit l4 into 'the motors 80, causing energiza- ,tion of the motors with the resultant actuation ume of fluid is displaced from the chamber 22 into the motors 86, causing a rapid energization of the motors, resulting in correspondingly rapid movement of the friction elements into engagement with the drums. As the piston 36 advances on its compression stroke, the pressure on the the invention, what I claim as new and desire fluid in the system is-quickly built up, due to reaction, to a predetermined degree, whereupon the pressure onthe fluid in the chamber 22 acting on the head 58 moves the piston it agalnst the head 28 of the chamber 24 and thereby establishes communication between the chamber 22 and the reservoir. Thereafter, as the' piston ll advances on its compression stroke, the fluid in the chamber 22 is displaced therefrom through the port 34 into the reservoir, and the fluid in the chamber 52 is displaced therefrom through the opening 82 in the sealing cup 12 into-the passage 16, thence through the fluid pressure delivery line 84 into the fluid pressure actuated motors 86, causing further energization of the motors with the resultant further activation of the brakes. l

- Upon conclusion of the braking operation, the foot pedal lever [I6 is released, and is returned to-its retracted position under the influence of the spring H0. This results in retracting the rod I04 and thrust pin 96, with the consequent release of the piston 36, whereupon the piston 36 is returned to its retracted position under the influence of the spring 10 assisted by the spring 64, the latter urging the piston 58 to its retracted position wherein the supply port 34 is normally closed.

During this operation, a partial vacuum is created in the chamber 22, and fluid is drawn from the reservoir through the port 34 into the chamber 24, thence through the passages 66 in the head 58 of the piston 58', past the sealing washer 68, into the chamber 22, thence through the passages 14, past the cup 18, into the chamber 52, completely filling the chambers. During this operation, fluid is also returning from the fluid pressure actuated motors l6 and the fluid pressure delivery lines connecting the motors to the passage It. This may result in the chamber 52 receiving a quantity of fluid in excess of its capacity, and in that event the excess fluid is displaced therefrom, through the port 54, into the chamber 22, thence through the port 32, into the reservoir.

,While this invention has been described in connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore. to be limited-only as indicated by the scope of'the appended claims.

Having thus described the various features of to secure by Letters Patent is:

lea fluid pressure producing device comprising a cylinder having a head and a supply port, a small piston reciprocable in the head having a part for control of the supply port and a fluid discharge passage extended therethrough, a relatively large piston reciprocable in the cylinder having a chamber receiving the small piston, and means for actuating the large piston.

2. A fluid pressure producing device comprising a cylinder having a head and a supply port, a

I pistonreciprocable in the head concentrically of the cylinder having a fluid outlet passage therethrough, a valve on the piston for control of the.

supply port, a piston reciprocable in the cylinder having a chamber receiving the first-mentioned piston, said chamber communicating with the fluid'outlet, and an actuator for the piston having the chamber therein.

3. A fluid pressure producing device comprising a cylinder having a head and a supply port, a piston reciprocable in the head concentrically of the I ble in the cylinder. having a chamber therein cylinder having a passage therethrough for the discharge of fluid from the device, means for limiting movement of the piston in both directions, means carried by the piston for control of the supply port and a second piston reciprocable in the cylinder having a chamber communi- .cating with the cylinder and receiving the first-' mentioned piston. r

4. A fluid pressure producing device comprising a cylinder having a head and a supply port, a piston reciprocable in the head concentrically of the cylinder having a passage therethrough provided with a fluid discharge port, means for limcylinder having a chamber communicating with the cylinder and-receiving the first-mentioned piston, means for the'passage oi fluid iromthe cylinder past the first-mentioned piston, means providing communication between the passage A in the cylinder reciprocable inthe head ofth'e v cylinder and the chamber in the second piston, and means for actuating the second-mentioned piston.

5. A fluid pressure producing device comprising a cylinder having a head and a supp y P 8 piston reciprocable in the head concentrically or the cylinder having a fluid discharge passage therethrough, means carried bythe piston for iting movement of the piston in both directions, means carried by the piston f I control of the supply port, a second piston re iprocable in the amazes- I 3 first-mentioned pistommeans providing for the flow of fluid from the cylinder into the chamber, means carried by the first-mentionedpiston for control of the flow of fluid into and from the chamber, means providing for communication between the chamber in thepiston andrthe passage in the piston reciprocable in the head of the cylinder, and manual means for activating the second-mentioned piston.

-7.- Afluid pressure producing device comprising a reservoir, a cylinder associated therewith having a head and a port communicating with the reservoir, a low pressure piston recipro'cable in the cylinder having a chamber therein communicating with the cylinder, a high pressure piston movable in the head of the cylinder having a part for control of the. port and another part commensurate the chamber in the low pressure piston, a fluid outlet passage for the device inthe high 'pressure piston communicating with the chamber in the low pressure piston, and means for actuating thelow pressure piston 8. A fluid pressure producing'device comprising a reservoir, a cylinder supplied therefrom having a head and a port communicating with the reservoir, a' large piston having a chamber therein 'reciprocable in the cylinder for creating pressure,

, a small piston movable in the head of the cylincontrolof the supply port, a second piston reciprocable in the cylinder having a chamber therein communicating with the cylinder and receiving the first-mentioned piston, means providing for flow of fluid from the cylinder'through the first-mentioned piston into the chamber,

means carried by the first-mentionedpiston for control of the flowlof fluid into and from the chamber, a communication between the fluid'discharge passage and chamber in the second piston, means controlling the passage, and means for actuating the second-mentionedpiston.

6. A fluid pressure producing device comprising a reservoir, a cylinder associated therewith hav ing a head and a port communicating with the reservoir, 9. piston reciprocable in the head concentrically of the cylinder having a passage therethrough, an outlet in the piston communicating with the passage, a valve carried by-the piston for control or the .port, a second piston reciprocacommunicating with the cylinder and receiving the 9. In a fluid pressure producing device, a reservoir, acylinder associated therewith having a head and a port communicating with the reserv o, ir, a high pressure piston reciprocable in the head of the-cylinder, means on the piston normally closing the port, a second piston reciprocable in the cylinder having a chamber therein communicating with the cylinder, a head on the first piston movable within the piston chamber relative'to thesecond piston, a fluid discharge passage through the flrst piston communicating.

with the chamber, and means for actuating-the second piston; 1

' HERBERT C. BOWEN. 

